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/*
* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
*
* Based on Rusty Russell's IPv4 MASQUERADE target. Development of IPv6 NAT
* funded by Astaro.
*/
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <limits.h> /* INT_MAX in ip_tables.h */
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter/nf_nat.h>
enum {
O_TO_PORTS = 0,
O_RANDOM,
O_RANDOM_FULLY,
};
static void MASQUERADE_help(void)
{
printf(
"MASQUERADE target options:\n"
" --to-ports <port>[-<port>]\n"
" Port (range) to map to.\n"
" --random\n"
" Randomize source port.\n"
" --random-fully\n"
" Fully randomize source port.\n");
}
static const struct xt_option_entry MASQUERADE_opts[] = {
{.name = "to-ports", .id = O_TO_PORTS, .type = XTTYPE_STRING},
{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
{.name = "random-fully", .id = O_RANDOM_FULLY, .type = XTTYPE_NONE},
XTOPT_TABLEEND,
};
/* Parses ports */
static void
parse_ports(const char *arg, struct nf_nat_range *r)
{
char *end;
unsigned int port, maxport;
r->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
if (!xtables_strtoui(arg, &end, &port, 0, UINT16_MAX))
xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--to-ports", arg);
switch (*end) {
case '\0':
r->min_proto.tcp.port
= r->max_proto.tcp.port
= htons(port);
return;
case '-':
if (!xtables_strtoui(end + 1, NULL, &maxport, 0, UINT16_MAX))
break;
if (maxport < port)
break;
r->min_proto.tcp.port = htons(port);
r->max_proto.tcp.port = htons(maxport);
return;
default:
break;
}
xtables_param_act(XTF_BAD_VALUE, "MASQUERADE", "--to-ports", arg);
}
static void MASQUERADE_parse(struct xt_option_call *cb)
{
const struct ip6t_entry *entry = cb->xt_entry;
struct nf_nat_range *r = cb->data;
int portok;
if (entry->ipv6.proto == IPPROTO_TCP ||
entry->ipv6.proto == IPPROTO_UDP ||
entry->ipv6.proto == IPPROTO_SCTP ||
entry->ipv6.proto == IPPROTO_DCCP ||
entry->ipv6.proto == IPPROTO_ICMP)
portok = 1;
else
portok = 0;
xtables_option_parse(cb);
switch (cb->entry->id) {
case O_TO_PORTS:
if (!portok)
xtables_error(PARAMETER_PROBLEM,
"Need TCP, UDP, SCTP or DCCP with port specification");
parse_ports(cb->arg, r);
break;
case O_RANDOM:
r->flags |= NF_NAT_RANGE_PROTO_RANDOM;
break;
case O_RANDOM_FULLY:
r->flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY;
break;
}
}
static void
MASQUERADE_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct nf_nat_range *r = (const void *)target->data;
if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
printf(" masq ports: ");
printf("%hu", ntohs(r->min_proto.tcp.port));
if (r->max_proto.tcp.port != r->min_proto.tcp.port)
printf("-%hu", ntohs(r->max_proto.tcp.port));
}
if (r->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" random");
if (r->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
printf(" random-fully");
}
static void
MASQUERADE_save(const void *ip, const struct xt_entry_target *target)
{
const struct nf_nat_range *r = (const void *)target->data;
if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
printf(" --to-ports %hu", ntohs(r->min_proto.tcp.port));
if (r->max_proto.tcp.port != r->min_proto.tcp.port)
printf("-%hu", ntohs(r->max_proto.tcp.port));
}
if (r->flags & NF_NAT_RANGE_PROTO_RANDOM)
printf(" --random");
if (r->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
printf(" --random-fully");
}
static int MASQUERADE_xlate(struct xt_xlate *xl,
const struct xt_xlate_tg_params *params)
{
const struct nf_nat_range *r = (const void *)params->target->data;
xt_xlate_add(xl, "masquerade");
if (r->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
xt_xlate_add(xl, " to :%hu", ntohs(r->min_proto.tcp.port));
if (r->max_proto.tcp.port != r->min_proto.tcp.port)
xt_xlate_add(xl, "-%hu", ntohs(r->max_proto.tcp.port));
}
xt_xlate_add(xl, " ");
if (r->flags & NF_NAT_RANGE_PROTO_RANDOM)
xt_xlate_add(xl, "random ");
xt_xlate_add(xl, " ");
if (r->flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY)
xt_xlate_add(xl, "random-fully ");
return 1;
}
static struct xtables_target masquerade_tg_reg = {
.name = "MASQUERADE",
.version = XTABLES_VERSION,
.family = NFPROTO_IPV6,
.size = XT_ALIGN(sizeof(struct nf_nat_range)),
.userspacesize = XT_ALIGN(sizeof(struct nf_nat_range)),
.help = MASQUERADE_help,
.x6_parse = MASQUERADE_parse,
.print = MASQUERADE_print,
.save = MASQUERADE_save,
.x6_options = MASQUERADE_opts,
.xlate = MASQUERADE_xlate,
};
void _init(void)
{
xtables_register_target(&masquerade_tg_reg);
}
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